An internal combustion engine is primarily thought of as a device to propel a vehicle. The internal combustion engine, however, also serves as a source of power generation for subsidiary needs. The result of this dual function is, of course, the use of the internal combustion engine in a dual capacity. As the efficiency of design increases, this dual capacity is more frequently utilized. The requisite control systems for engines in vehicles were initially designed for transportation. As the use of internal combustion as a source of subsidiary power generation increases, there is a need to redesign the control systems to account for this secondary function.
A need has developed for a fast idle device for an internal combustion engine which operates in a failsafe fashion. A device is required which can, upon command, produce a second given idle speed at a rate which can be predetermined. As an example of these needs, consider an ambulance during operation. With the present idle control system devices, the power requirements of a potentially life saving machine might be higher than the engine is capable of producing at its normal idle speed, thereby stalling the engine and cutting off power entirely. Another example is the use of a vehicle which includes a hydraulically operated device where the engine speed must be high enough to develop hydraulic working pressure. In such a case the operator of the vehicle would prefer to have a second idle speed, which would fall in the desired R.P.M. range to develop the hydraulic pressure required.
One other particular concern for engine power is that it be available when necessary. Often a human operator is not available to change the idle speed of the engine. There exists a need for a fast idle device which can be either manually applied by the operator or automatically applied by a second machine which senses the condition of need. There also exists a need for a device which quickly and efficiently brings an engine up to a second predetermined idle speed.